Powder form waving compositions comprising a metal complex of thioglycollic acid anda chelating agent



United States Patent 3,193,463 PGWDER FGRM WAVING CQWUSHIONS Cilia l- PRISING A METAL CGMPLEX 0F THEQGLY- COLLIC AClll) AND A CHELATKNG AGENT Henry C. Schweizer, Cincinnati, (thin, assignor to The Procter & Gamble Company, Cincinnati, Ohio, a conporation of (lhio No Drawing. Filed Feb. 6, 1963, Ser. No. 256,527 18 Claims. (Cl. 167-871) This invention is concerned with a composition suitable for preparation of solutions for use in cold permanent Waving of hair. More particularly, it is concerned with a substantially odor free hair waving composition in powder form containing as a waving agent precursor a watersoluble metal-thioglycolic acid complex or a water-soluble salt thereof as hereinafter more particularly described, and a water-soluble chelating agent.

Currently available hair waving compositions generally are packaged as liquids or as powders. If the composition is in powder form, a liquid (generally water) must be added to dissolve the powder before it can be applied to the hair.

Waving compositions in powder form containing ammonium, substituted ammonium and alkali metal thioglycolates or mercapto-alkanoic compounds as the waving agent (most commercial waving compositions contain one or the other of these compounds) have been found to be unstable and lose their waving properties and also develop disagreeable odors on storage, due to oxidation and decomposition. Various non-alkali metal salts of thiogiycolic acid have been suggested for use in waving compositions which are more stable than the above-mentioned thioglycolates and therefore do not present odor problems. However, those compounds which have been found to be resistant to oxidation and decomposition in waving compositions do not effectively wave the hair.

It is an object of this invention to provide an improved waving composition in powder form which is stable to oxidation and decomposition, and which does not develop disagreeable odors on standing or when in storage.

It is also an object of this invention to provide a waving composition in powderform which, although stable and essentially non-odor forming, nevertheless eifectively waves hair when in aqueous solution and applied thereto.

It is a still further object of this invention to provide a process for waving the hair wherein aqueous solutions containing, respectively, a waving agent precursor and a waving agent activator are applied sequentially to the hair, whereby the hair configuration is permanently altered due to the conjoint action of these components on the hair.

Other benefits of this invention will be apparent from the following description.

It has now been found that a stable, essentially odor free powdered waving composition can be prepared which comprises (1) a water-soluble metal-thioglycolic acid complex or water-soluble salts thereof wherein the metal is selected from the group consisting of zinc, calcium, strontium, barium, cadmium, aluminum, and nickel and (2) ,an aminopolycarboxylic acid or water-soluble salt thereof having a metal chelate formation constant at least equal to the stability constant of the corresponding metal-thicglycolic acid complex, such that on solution of the waving composition substantially all of the metal ion is removed from the metal-thioglycolic acid complex through the formation of a stable chelate with the aminopolycarboxylic acid, said composition having a pH between about 8.5 and about when in aqueous solution.

The water-soluble metal-thioglycolic acid complexes and water-soluble salts thereof which can be used as the waving agent precursor in the compositions of this invention are those in which the metal of the metal-thioglycolic acid 3,193,463 Patented July 6, 1965 complex is selected from the group consisting of zinc, calcium, strontium, barium, cadmium, aluminum and nickel, and the salt forming cation is selected from the group consisting of alkali metal, ammonium, and substituted ammonium such as lower alkan-olamino, ions. These complexes can be prepared in a number of different ways. Generally, however, the metal-thioglycolic acid complex is formed by reacting the metals as bases or oxides with thioglycolic acid in an aqueous medium, in a 1:2 or 1:3 mole ratio depending on whether the metal is divalent or trivalent. The water-soluble salts are prepared by reacting the metals as bases or oxides with thioglycolic acid (same mole ratios as above) in the presence of the salt forming cation or with the monovalent alkali salts of thioglycolic acid. The complexes thus formed are then reduced to the solid state by spray drying, concentrating the solution to a syrupy consistency by vacuum evaporation followed by open air evaporation, and/ or precipitating them from solution with acetone or alcohol.

In simplified form, the etal-thioglycolic acid complex and water-soluble salts thereof can be represented as follows, M(SCH COOX+),, where M rep-resents a metal selected from the group consisting of zinc, calcium, strontium, barium, nickel, aluminum, and cadmium, X represents hydrogen, alkali metal, ammonium or substituted ammonium ions, and n is 2 or 3, depending on Whether M is divalent or trivalent. This invention is in no way to be limited by the structural formula set forth above, however.

Specific methods of preparation of the diammonium salt of the zinc bis-thioglycolic acid complex, a compound representative of those employed in the practice of this invention, are set forth below.

EXAMPLE L-DIAMMONIUM SALT OF ZINC BIS- THIOGLYCOLIC ACID 16.3 g. of reagent grade zinc oxide (0.2 mole) were added to 69.9 g. of ammonium thioglyc-olate (0.4 mole) diluted with 50 ml. of distilled water with vigorous stirring and cooling to minimize temperature rise. In order to prevent oxidation, this step was carried out under a blanket of nitrogen. Additional distilled water was added dropwise until a clear, slightly pinkish solution resulted. The solution was then transferred into a freeze-drying apparatus and concentrated until it had attained a syrupy consistency. The resultant diammonium salt of the zinc bisthioglycolic acid complex was then precipitated with acetone. The crystalline precipitate was separated by filtration, washed with acetone, and dried in air. The yield was over 99%, but the product was not odorless. A small amount of this salt was dissolved in distilled water and acetone was added until a slight haziness persisted. Overnight, well formed, relatively large crystals of practically odorless diammonium salts of zinc bis-thioglycolic acid were obtained. The compound remained stable and essentially odor free for 1 month when stored in an open beaker at F. and 30% relative humidity.

EXAMPLE lL-DlAMMONIUM SALT OF ZINC BIS-THICGLYCOLIC ACID 16.3 g. of reagent grade zinc oxide (0.2 moles) were suspended in 52.65 g. of thioglycolic acid (70% soln., 0.4 mole) and 50 ml. of distilled water. No reaction between the two reagents was observed until concentrated NH OH was added. Ammonium hydroxide was added drop-wise while cooling (to minimize temperature rise) until the pH of the solution had reached 8. Following this step the procedure was the same as described in Example I, i.e., the solution was then transferred to a freeze-drying apparatus, concentrated and the resultant acetone precipitated crystalline diammoninm zinc bis-thioglycolate was separated and washed. When dried and stored this compound exhibited essentially the same stability and odor characteristics as did the compound in Example I.

A preferred waving agent precursor for use in the compositions of this invention is the dipotassium salt of zinc bis-thioglycolic acid. Other compounds which find utility are, for example, zinc bis-thioglycolic acid, the diammonium salt of zinc bis-thioglycolic acid, the dipotassium salt of strontium bis-thioglycolic acid, strontium bis-thioglycolic acid, nickel bis-thioglycolic acid, the dipotassium salt of nickel bis-thioglycolic acid, the dipotassium salt of calcium bis-thioglycolic acid, calcium bis-thioglycolic acid, the diammonium salt of barium bis-thioglycolic acid, barium bis-thioglycolic acid, the di(monoethanolamine) salt of cadmium bis-thioglycolic acid, cadmium bis-thicglycolic acid, the tripotassium salt of aluminum tris-thioglycolic acid, aluminum tris-thioglycolic acid, the disodium salt of zinc bis-thioglycolic acid, the di(monoethanolamine) salt of zinc bis-thioglycolic acid, the diammonium salt of nickel bis-thioglycolic acid, the di(triethanolamine) salt of strontium bis-thioglycolic acid, the disodium salt of calcium bis-thioglycolic acid, the diammonium salt of calcium bis-thioglycolic acid, the di(monoethanolamine) salt of barium bis-thioglycolic acid, the diammonium salt of barium bis-thioglycolic acid, and the triammonium salt of aluminum tris-thioglycolic acid.

The aminopolycarboxylic acids or water-soluble salts thereof employed as sequestering or chelating agents in this invention can be any which in aqueous solution act to break the metal-tosulfur bond and complex the metal of the mctal-thioglycolic acid or metal-thioglycolate complex to form a metal chelate, yielding thioglycolate or thioglycolic acid radicals having free sulfhydryl groups which, as is well known, reduce the disulfide cross-linkage of hair keratin permitting permanent modification of the hair configuration. It is thus essential to the practice of this invention that the chelating agents have metal chelate formation constants with the metal of the metal-thio glycolic acid or metal-thioglycolate complex equal to or greater than the stability constant of the metal-thioglycolic acid complex or salt thereof with which they are admixed. Preferably, the formation constant of the metal chelate compound is at least 10 times the stability constant of the corresponding metal-thioglycolic acid or metal-thieglycolate complex.

The preferred sequestering or chelating agents for use in the composition of this invention are the sodium salts of ethylenediaminetetraacetic acid (such as mono-, di-, tri-, and tetrasodium ethylenediaminetetraacetate). Other suitable agents include, for example, ethylenediaminetetraacetic acid and other aminopolycarboxylic acids such as ethylenediamine-N,N'-dipropionic-N,N-diacetic acid,

l,Z-diaminocyclohexane-N,N-tetraacetic acid,

diethylenetriaminepentaacetic acid,

N-hydroxyethylenediaminetriacetic acid, and

ethylene-bis-N,N-2 aminomethyl) -pyridine-N,N'-diacetic acid.

Other operable chelating or sequestering agents include the alkali metal, ammonium and substituted ammonium i.e. lower alkanolamino, salts of these acids, such as tetrasodium ethylenediamine-N,N'-dipropionate-N,N'-diacetate,

tetraammonium ethylenediamine-N,N-dipropionate- N,N'-diacetate,

the di(monoethanolamine) salt of ethylenedia1nine-N,N-

dipropionic-N,N'-diacetic acid,

the disodium salt of 1,2-diaminocyclohexane-N,N'-

tetraacetic acid,

the di(isopropanolamine) salt of 1,2-diaminocyclohexane- N,N'-tetraacetic acid,

'tetraammonium 1,Z-diaminocyclohexane-N,N'-tetraacetate,

'pentasodium diethylcnetriaminepentaacetate,

the tetrapotassium salt of diethylenetriaminepentaacetic acid,

the tri(diethanolarnine) salt of diethylenetriaminepentaacetic acid,

the tetraammonium salt of diethylenetriaminepentaacetic acid,

trisodium N-hydroxyethylenediaminetriacetate,

triammonium N-hydroxyethylenediaminetriacetate,

the di(monoethanolamine) salt of N-hydroxyethylenediaminetriacetic acid,

disodium ethylene bis-N,N'-2(aminomethyl)-pyridine- N,N'-diacetate,

diammonium ethylene bis-N,N-2(aminomethyl)-pyridine- N,N'-diacetate, and

di(triethanolamine) ethylene bis-N,N'-2(aminomethyl)- pyridine-N,N-diacetate.

As is the case With the metal-thioglycolic acid complexes or salts thereof, these compounds in actual usage will be dissolved in aqueous solutions having a pH ranging from about 8.5 to about 10.0; therefore, the acid form of the chelate will be instantaneously neutralized when dissolved. Thus it is immaterial whether the acid or salt form of the chelating compound is used in the compositions of this invention.

The relative stability or formation constants of exemplary salts of metal-thioglycolic acid complexes which can be used in the compositions of this invention and the corresponding metal chelate compounds are set forth in Table 1 below. These constants (pK) can be determined by potentiometric and/ or polarographic methods well known in the art (see Organic sequestering Agents, Chaberek and Martell, chapter 4, John Wiley & Sons (1959)). The terms stability constant and formation constant used herein can be used interchangeably but for the purpose of placing in perspective the mode of action of the components of the composition described herein, the constant of the metal-thioglycolic acid or metal-thioglycolate complex is referred to as the stability constant whereas the constant of the metal chelate is referred to as the formation constant.

52 2 palculated according to method of Li and Manning, .T.A.C.S., 77, bg ziiii ed from Appendix 3, Organic sequestering Agents, Chaberek & Martell, John Wiley 6: Sons (1959). (lggiilculatcd according to method of D. L.Leussing, J'.A.C.S., 80, 418d The comparisons above are only exemplary of the possible combinations which can be used in this invention.

Since the stability or formation constants of these complexes are defined as the equilibrium constant for the reaction in which the metal chelate is formed from the hydrated metal ion and the most basic (most highly dissociated) form of the chelating agent, it will be readily understood that the stability constant of the metal chelate is independent of the particular salt form being used, i.e., it is immaterial whether, for example, the disodium salt of ethylenediaminetetraacetic acid (Na EDTA) or the acid form (H EDTA) is used, to determine the stability constant of the ZnEDTA complex, as the acid anion of EDTA is the reactive part and not the H+ 0r Na+ ions. Thus, the values in the table above are essentially the same whether the acid or salt form of the chelating agent is used to determine the constant.

It can be observed from the above table that the formation constants of the metal-chelate compounds formed when the compositions of this invention are dissolved in water or other aqueous liquids such as milk are at least equal to and in most instances or more times greater than the stability constants of the corresponding metal thioglycolic acid complexes. Any Water-soluble alkali metal, ammonium or substituted ammonium salt of the zinc bis-thioglycolic acid or nickel bis-thioglycolic acid complexes, for example, can be used in conjunction with aminopolycarboxylic acids such as diethylenetriaminepentaacetic acid, ethylenediaminetetraacetic acid, or ethylene bis N,N'-(2-aminomethyl) pyridine-N,N'-diacetic acid and water-soluble salts thereof in an aqueous solution having a pH within the range herein specified to attain the objects of this invention.

When used alone in aqueous solution at a pH within the range herein specified, the metal-thioglycolic acid complexes and water-soluble salts thereof usedin the present compositions have very poor waving characteristics and cannot be employed as waving agents because the SH group (sulfhydryl) is not available for reduction of the keratin of the hair. However, when a powder containing the water-soluble rnetal-thioglycolic acid complexes or water-soluble salts thereof and the metal chelating or se questering agents of this invention is dissolved in water, the metal-to-sulfur bond of the thioglycolic acid complex or salt thereof is broken and the thioglycolate ion is activated. The degree of activation, of course, depends upon the stability constant of the metal-thioglycolic acid complex or salt thereof, the formation constant of the corre sponding metal chelate and the relative quantities of these components present in solution. An especially preferred waving composition is comprised of a 1:1 mole ratio of the diammonium salt of zinc bis-thioglycolic acid complex and tetrasodium ethylenediaminetetraacetate.

It has long been known that waving compositions based on thioglycolic acid or salts are most effective when the pH of the waving solution ranges from about 8.5 to about 10; therefore, as thioglycolate ions are liberated in the solutions of the waving compositions of this invention due to the chelating action of the aminopolycarboxylio acids and salts described herein, it is also essential that the solutions of the waving compositions of this invention have pH values within this range. The optimum pH for hair waving depends on the concentration of thio glycolate ion liberated in solution and the time selected for the waving process. The time of waving has been described as being shorter with higher concentrations of thioglycolate ions, and longer with lower concentrations. The time of waving is also less at higher pH values and longer at lower pH values. Moreover, effective waving can be accomplished at lower pH values if the concentration of the thioglycolate ions is increased. If the concentration of the thioglycolate ion is decreased the pH values should be higher to obtain efiective Waving action. A particularly desirable range is from pH 8.5 to pH 9.5.

Any suitable alkali may be used to adjust the pH but it is preferred to use a weak base as a substantial portion of the alkali, thereby providing desirable buffering capacity. Suitable weak bases have dissociation constants of less than 10- and preferably less than l0 they include ammonia, monoethanolamine, diethanolamine, tris hydroxymethylaminomethane and 2-amino-2-methyl-1,3- propane diol. Triethanolamine and glyceryl amine are further examples of bases which may be used. Ammonia and monoethanolamine are especially preferred Weak bases. Mixtures of weak bases can be employed, and it is often advantageous to do so. Examples of strong bases which may be used in minor proportions in conjunction with a major proportion of weak bases in this invention are the alkali metal hydroxides, such as sodium hydroxide, lithium hydroxide, and potassium hydroxide. A portion of strong bases are usually preferred when the waving composition is in powder form as is exemplified herein.

While the factors affecting the ability of an aminopoly carboxylic acid or salt to sequester or chelate the metal ion from the metal-thioglycolic acid complex or salts thereof are many, it may be generally stated that those aminopolycarboxylic acids and salts having the greater number of available carboxyl groups are the most effective sequestrants or chelating agents. Consequently, if an aminopolycarboxylic acid or salt is used which has only three available carboxyl groups instead of four, it will be-necessary to employ a greater proportion of chelating agent to obtain good sequestration and therefore good waving action.

The following examples are merely to illustrate the effectiveness of various compositions of this invention and should not be considered as limiting thereof.

EXAMPLE 111 In this example the efliccacy of various hair waving compositions of this invention is shown by means of the Switch Wave Test. This test is conducted as follows: Uniform individual switches of hair are washed and permitted to dry. They are then wound upon small mandrels and saturated with the waving lotion to be tested.

After thirty minutes the hair switches are resaturated with the waving lotion and are left in this condition for ten minutes. The switches are then rinsed for one-half minute with distilled water, and wrapped in a dry towel for thirty minutes. A conventional neutralizer (sodium perborate) is then applied and the hair switches are again rinsed with water. The waved switches are then unwound and the wave grade measured.

To determine the relative degree of wave formation, the test switches are compared to a Wave grade photoscale which is comprised of a composite photograph showing nine wet switches of hair which have been cold waved to varying degrees of tightness in approximately a linear relationship by adjusting either the time of waving, strength of the waving lotion or both. The switches were made from the same type of ordinary human -hair and were six free inches in length (six inches of hair available for waving), thirty-six millimeters wide at the top and Weighed 2 grams. All the switches were wound on a 4 millimeter diameter mandrel in the cold waving process. Arbitrary values from 0 to 8 have been assigned to the switches ranging from no wave (0) to over wave (8). A good commercial waving lotion yields a value of about 3.0 to about 5.0 on this scale, depending on the concentration of waving agent in the lotion. Wave grades over about 6 are not desirable as the curl is too tight and not acceptable to the majority of consumers.

T able II N Compositions of waving lotions Curl grade pH of Waving lotions 6.55 g. diammoniurn salt of zinc bisthioglycolio acid.

6.90 g. disodium salt of cyclohexanediaminetetraacetic acid.

7.15 g. isopropanol amine 79.40 g. water 6.85 g. diammonium salt of zinc bisthioglycolic acid.

2.30 g. monoethanolarnine 90.85 g. water 13.8 g. diammoniurn salt of zinc bisthioglycolic acid.

86.2 g. water (3A and 3B applied to hair in sequence in 1:1 by weight proportions at a 30n1inute interval).

13.9 g. disodium salt of cyclo-hexanediaminetetraacetic acid.

14.3 g. isopropanol amine 71.8 g. water In Table II above, the solutions used were made by dissolving the essential compounds used in the compositions of this invention as powders, i.e., the metal-thioglycolic acid complex and the chelating agent, in water with the pH buffering compounds being added in the form of liquids. Thus it is seen that the Solution 1 is prepared from an exemplary powdered waving composition of this invention. Solutions 3A and 3B are exemplary of solutions which can be used in the waving process of this invention.

It can be seen from the above example that a solution of a representative waving composition of this invention (1) containing the diammonium salt of zinc bis-thioglycolic acid and the disodium salt of cycloheXanediaminetetr-aacetic acid has the same waving eifectiveness as a good commercially available waving composition, whereas the lotion containing substantially the same concentration of the diammonium salt of zinc bis-thioglycolic acid without a chelatiug agent (2) has very poor waving characteristics. While in dry powder form, the diammonium salt of zinc bis-thioglycolic acid in admixture with the disodium salt of c'yclohexanediaminetetraacetic acid has essentially no ordor even after prolonged storage and is stable against decomposition and oxidation. It can also be seen that the hair can be treated sequentially with solutions containing the waving agent precursor and the chelating agent (3A and 3B) in accordance with the process of this invention, rather than applying both simultaneously, with good results.

' EXAMPLE 1V Another Switch Wave Test essentially duplicating the conditions of the test in Example III above was made using different lotions. The term Crest Distance as used in the table represents the average distance between wave crests measured in inches and is simply another means of measuring the effectiveness of the waving composition (the number of measurable crest distances in a switch varies from about 4 to about 7 depending on the tightness of the wave, i.e., the tighter the wave the greater the number of crests). The shorter the distance between crests the more efiective the waving composition. A good commercial waving lotion yields a Crest Distance of from about .69 to about 1.00 inch.

Table 3 Crest distance average Lotion 26.3 g. of a solution of the diammonium salt of zinc bisthioglycolie acid equivalent to a 10.6% by wt. solution of thioglycolic acid.

17.7 g. of a solution consisting of 40.8% 4

disodium salt of ethylenediaminetetraacetic acid, 35.1% monocthanolamine, and 24.1% water.

16.0 g. water 29.2 g. of a solution or the diammonium salt of zinc bisthioglycolic acid equivalent to a 10.6% by wt. solution of thioglycolic acid.

19.7 g. of a solution consisting of 40.8%

disodium salt 01' ethylenediaminetetraaeetic acid, 35.1% monoethanolamine, and 24.1% water.

11.1 g. water .1

32.1 g. of a solution of the diammonium salt of zinc bisthioglycolie acid equi valent to a 10.6% by wt. solution of thioglycolic acid.

27.7 g. of a solution consisting of 40.8%

disodium salt of ethylenediaminctetraacctlc acid, 85.1% monoethanolainine, and 24.1% water.

4.7 g. Water In Table 3 above, the waving lotions were prepared by dissolving the two primary components of the compositions of this invention, as powders, in individual water solutions adjusted to the proper pH. The solutions were then combined to make the waving lotions to be tested. It is seen from Table 3 that the primary components of the compositions of this invention when in aqueous solution have essentially the same waving properties as commercially available waving preparations. There is a minimum of odor associated with the waving compositions of this invention in powder form, even after prolonged storage. Moreover, the waving agent precursor is readily activated on the addition of water even after a long period of storage. Substantially the same results are achieved using diammonium calcium bis-thioglycolatc or dipotassium barium bis-thioglycolate as the waving agent precursor.

EXAMPLE V Another test was run using the Switch Wave technique described previously in Example III (same testing conditions) which compared a solution of the diammonium salt of zinc bis-thioglycolic acid tested with and without the disodium salt of ethylenediaminetetraacetic acid, an excellent chelating agent for use in the compositions of this invention.

Table 4 Percent thioglycolic acid equivalent Curl gradcs Solution 12.80 parts by wt. diammonium salt of zinc bisthioglycolic acid.

9.92 parts by wt. disodium salt of ethylenediaminetetraacctic acid.

77.28 parts by weight water pH adjusted to about 9.2 with ammonium hydroxide.

12.80 parts by weight diammonium salt of zinc bisthioglycolic acid. 4. 3 0.0 87.20 parts by weight water pH adjusted to about 9.2 with arm monium hydroxide.

It can be seen that in this particular example the waving composition of this invention containing the diammonium salt of zinc bis-thioglycolic acid complex and the salt of ethylenediaminetetraacetic acid gives good results while the diammonium zinc bis-thioglycolic acid complex solution without the chelating agent has no waving power.

EXAMPLE VI Another Switch Wave Test was run duplicating the test conditions of Example III except as indicated.

Table 5 Curl grades (3 replicates) Solution my 15.0 g. of a solution of the diammonium salt of zinc bis-thioglycolic acid equivalent to a 10.6% by wt. solution of thioglycolic acid.

10.08 g. of a solution consisting of 40.8%

tetrasodium ethylenediaminetetraacetate, 35.1% monoethanolamine, and 24.1% water.

11.1 g. water pH 9.2. p

29.2 g. of a solution of the diammonium salt of zinc bis-thioglycolic acid equivalent to a 10.6% by wt. solution of thioglycolic acid.

19.7 g. of a solution consisting of 40.8%

tetrasodium ethylenediarninetetraacetate, 35.1% monoethanol amine, and 24.1% water.

111.11 g. water 32.6 g. of a solution of the diammonium salt of zinc bis-thioglycolic acid equivalent to a 10.6% by wt. solution of thioglycolic acid.

22.7 g. of a solution consisting of 40.8%

tetra-sodium ethylenediaminetetraacetate, 35.1% monoethanolamine, and 24.1% water.

4.7 g. water The reference to timing in the example above refers, respectively, from left to right, to the time the curls set after the first saturation until they are reswturated, the time the curls set after resaturation until they are rinsed with water, and the time the curls are dried after rinsing.

The waving lotions in Table 5 Were made in the same manner as were the lotions in Table 3, i.e., the powdered salt of the nietal-thioglycolic acid complex and the chelating agent (the essential components of the compositions of this invention) were dissolved in separate water solutions and then the solutions were combined to form the Waving lotion. The mixture of the primary components of the lotions when in powder form are representative of the waving compositions of this invention.

From this example, it can be seen that good waves are obtained using the diarnmonium salt of zinc bisthioglycolic acid complex/chelating agent waving lotions made from the Waving compositions of this invention, yet the odor level of the waving compositions when in powder form is much lower and the compositions are stable against oxidation and deterioration.

The results of the foregoing examples indicate that aqueous solutions containing the activated metalthioglycolic acid complex or water-soluble salts thereof resulting from the conjoint action of the essential components of the compositions of this invention are as effective as comparable com ercially available waving lotions. As can be seen by the examples above, metal thioglycolic acid complexes or salts thereof themselves are relatively ineffective as waving agents and must be activated by chelating the metal cation.

EXAMPLE VII A waving composition in powdered form is prepared having the following composition:

Percent by weight Dipotassium salt of zinc bis-thioglycolic acid 32.7 Tris-hyd-roxymethylamino methane 30.0 Sodium hydroxide 2.7 Tetrasodiurn ethylencdiaminetetraacetate 32.7 Perfume 1.9

The powder is stable and has very little odor even after prolonged storage when stored in a moisture-proof packet. When dissolved in water such that in solution the keratin reducing agent is present in an amount equivalent to about thioglycolic acid, a good wave of superior lasting quality is obtained, and the hair is left in excellent condition. All or part of the dipotassium zinc bis-thioglycolate can be replaced by diammonium zinc bis-thioglycolate, calcium bis-thioglycolic acid, disodium zinc bis-thioglycolate, diammonium calcium bis-thioglycolate, barium bis-thioglycolic acid, dipotassiurn barium bis-thioglycolate and diammonium nickel bis-thioglycolate with no substantial change in stability or waving properties, provided the pH of the composition in solution is kept within the range herein specified. Similarly, the chelating agent can be replaced by ethylenediaminetetraacetic acid, pentasodium diethylene triaminepentaacetate or the disodium salt of cyclohexanediaminetetraacetic acid with substantially equivalent results.

EXAMPLE VIII A waving composition in powder form is prepared having the following composition:

Percent by weight Di(monoethanolamine) salt of zinc bis-thioglycolic acid 32.2 Tris-hydroxymethylaminomethane 33.0 Pentasodium diethylenetriaminepentaacetate 33.0 Perfume 1.8

This powder is stable on standing and has very little oder. When dissolved in water such that in solution the waving agent is present in an amount equivalent to about 5% thioglycolic acid and applied to the hair, a good wave is obtained and the hair is not harmed. The hair waving composition of this example possesses substantially the same desirable properties when di(monoethanolamine) strontium, diammonium cadmium or di(monoethanolamine) calcium bis-thioglycolate or aluminum tris-thioglycolic acid or barium bis-thioglycolic acid are used in place of di(rnonoethanolamine) zinc bis-thioglycolate with suitable adjustment in pH.

W EXAMPLE IX A powder composition having the following formula is prepared:

. Percent Dipotassium calcium bis-thioglycolate 33.0 3-amino-2 methyl-1,3-propane diol 33.0 Pentasodium diethylene triaminepentaacetate 33.0 Perfume 1.0

This powder also has good stability on standing and is essentially odor free. It gives an excellent hair wave when dissolved in water and employed in the normal fashion The chelating agent employed in this example, pentasodium diethylenetriaminepentaacetate, can be replaced in whole or in part by tetrasodium ethylenediaminetetraacetate, disodium ethylenediamine-N,N'-dipropionic-N,N'-diacetate, :disodium ethylene bis-N,N'- 2(amino ethyl)pyridine-N,i-I'-diacetate or trisodium N-hydroxyethylene-diaminetriacetate with comparable results.

From the standpoint of ease and cost of packaging it is preferable to mix the powdered metal-thioglycolic acid complexes or salts thereof and the chelating agents plus the other additives together and pack them in a single moisture-proof packet; however, it is also possible to pack the waving agent precursor and chelating agent in separate packets in order to avoid any possibility that moisture might get into a packet containing both compounds thereby causing activation of the waving agent precursor with the subsequent possibility of its om' dation and decomposition prior to the time of its application to the hair. By packing the waving agent precursor and the chelating agent in separate packets it is also possible to dissolve each in solution separately, apply the nonwaving metal-thioglycolic acid or salts thereof to the hair and follow this up with an application of an alkaline solution of the chelating agent buffered at about pH 8.5 to 10 to achieve the desired wave grade.

It is also possible to pack the waving agent precursor and the chelating agent in the same box or container with the source of the waving agent in an individual moisture proof packet and the chelating agent in aqueous solution in a glass or plastic bottle.

In order to obtain the maximum benefit in odor reduction, the waving lotion prepared from the compositions of this invention should be applied to the curl shortly after the powder is dissolved in the liquid as odors tend to develop as the liquid stands. The powder can be dissolved in the liquid before the lotion is applied to the hair, or the powder can be imbedded in end papers which are wound around the curl and the solubilizing liquid can then be applied directly to the curl where it saturates the end paper and frees thioglycolate ions from the metalthioglycolic acid or metal-thioglycolate complex. In this manner odors do not have time to develop. A preferred process of waving hair in accordance with this invention which can be employed if each essential component is packed separately is to saturate the curl arranged in the desired configuration with a solution containing only the waving agent precursor described herein at a pH ranging from about 8.5 to about 10, and subsequently, applying a solution containing the chelating aminopolycarboxylic acid or salts thereof buffered to a pH within the range from 8.5 to 10. On the hair the chelating agent then complexes the metal of the metalthioglycolic acid complex or salt thereof, breaks the metalto-sulfur bond yielding thioglycolate ions containing the free sulfhydryl groups which then reduce the disulfide cross-linkage of hair keratin allowing the hair configuration to be altered. The curl is then fixed or neutralized by rinsing the hair with conventional neutralizers such as sodium perborate or hydrogen peroxide.

In carrying out the process of this invention, solutions containing, respectively, the waving agent precursor and the chelating agent can be applied to the hair strand before or after winding the hair on a mandrel, by soaking the hair in any desired manner; however, it is desirable to apply the solution containing the chelating agent after the hair strand has been wound on a mandrel, to insure maximum waving. After the latter solution is applied, suflicient time is allowed for activation of the waving agent and reaction with the hair keratin. The hair is then water rinsed and thereafter a fixing or neutralizing solution such as is described in U.S. 2,736,323 is applied to assure fixing of the hair in its new configuration.

In this instance it is desirable to saturate the hair curl with the solution of the chelating agent within about onehalf hour after the curl has been saturated with the solution containing the metal-thioglycolic acid complex or salt thereof as it is not desirable to leave alkaline materials on the hair for too long a period of time because of possible hair damage. The solutions should be applied so that the ratio of metal-thioglycolic acid complex or salt thereof to chelating agent is the same as it would be were the two compounds present in the same solution as in dissolution of the waving compositions of this invention.

The waving powder of this invention containing the water-soluble metal-thioglycolic acid complex or watersoluble salt waving :agent precursor and chelating agent are preferably packaged so that on dissolution the watersoluble metal-thioglycolic acid complex or water-soluble salts thereof are present in solution at a level equivalent to from 1% to about thioglycolic acid by weight based on the total solution and the chelating agent is present in the same quantity, i.e., about 1% to about 10% by weight when in solution. The preferred compositions, when dissolved in water, contain the waving agents at a level equivalent to from about 3% to about 6% thioglycolic acid.

Various minor ingredients can be added to make the product pleasant to use or to leave the hair in particularly desirable condition. Perfumes and emulsifiers are usually incorporated in the compositions of this invention.

What is claimed is:

1. A composition in powder form suitable for use, when in aqueous solution, in the cold permanent waving of hair comprising:

(A) at least one member selected from the group consisting of a water-soluble thioglycolic acid complex of a metal ion and water-soluble alkali metal, ammonium and lower alkanolamino salts thereof wherein the metal ion is selected from the group consisting of zinc, calcium, strontium, barium, cadmium, aluminum, and nickel, and

(B) a chelating agent selected from the group consisting of water-soluble polyaminopolycarboxylic acids and alkali metal, ammonium and lower alkanolamino salts thereof, said chelating agent having a metal chelate formation constant with the metal ion of component (A) at least equal to the stability constant of the corresponding metal ion complex of (A), and being present in at least an amount such that on solution of the powder a substantial proportion of the metal ion is removed from the metal ion complex of (A) through the formation of a more stable chelate with said chelating agent, said composition having a pH within the range from about 8.5 to about 10 when in aqueous solution.

2. The composition of claim 1 wherein the water-soluble salt of 1a thioglycolic acid complex is the dipotassium salt of zinc bis-thioglycolic acid.

3. The composition of claim 1 wherein the Water-soluble salt of a thioglycolic acid complex is the diammonium salt of zinc bis-thioglycolic acid.

4. A composition in powder form suitable for preparation of solutions for use in the cold permanent waving of hair consisting essentially of the diammonium salt of zinc bis-thioglycolic acid and tetrasodium ethylenediaminetetraacetate, said components being employed at a ratio of about 1:1 by moles.

5. A process for permanently changing the configuration of the human hair including the steps of imparting the desired configuration to the hair and sequentially applying thereto aqueous solutions of (1) at least one member selected from the group consisting of a water-soluble thioglycolic acid complex of a metal ion and water-soluble alkali metal, ammonium and lower alkanolamino salts thereof wherein the metal ion is selected from the group consisting of zinc, calcium, strontium, barium, cadmium, aluminum, and nickel, and (2) a chelating agent selected from the group consisting of a water-soluble polyarninopolycarboxylic acid and alkali metal, ammonium, and lower alkanolamino salts thereof, said solution having a pH of from about 8.5 to about 10, said chelating agent having a metal chelate formation constant with the metal ion of the metal ion complex of (1) at least equal to the stability constant of the corresponding metal complex of (1), and then fixing said configuration by neutralization.

6. The process of claim 5 in which the water-soluble thioglycolic acid complex is an aqueous solution of the dipotassium salt of zinc bis-thioglycolic acid.

7. The composition of claim 1 wherein the chelating agent is ethylenediaminetetraacetic acid.

8. The composition of claim 1 wherein the chelating agent is ethylenediamine-N,N'-dipropionic-N,N-diacetic acid.

9. The composition of claim 1 wherein the chelating agent is 1,2-diaminocycl0heXane-N,N'-tetraacetic acid.

10. The composition of claim 1 wherein the chelating agent is diethylenetriaminepentaacetic acid.

11. The composition of claim 1 wherein the chelating agent is N-hydroxyethylenediaminetriacetic acid.

12. The composition of claim 1 wherein the chelating agent is ethylene-N,N'-2(aminomethyl)-pyridine-N,N-diacetic acid.

13. The process of claim 5 wherein the chelating agent is ethylenediaminetetraacetic acid.

14. The process of claim 5 wherein the chelating agent is ethylenediamine-N,Ndipropionic-N,N'-diacetic acid.

15. The process of claim 5 wherein the chelating agent is 1,2-diaminccyclohexane-N,N-tetraacetic acid.

16. The process of claim 5 wherein the chelating agent is diethylenetriaminepentaacetic acid.

17. The process of claim 5 wherein the chelating agent is N-hydroxyethylenediaminetriacetic acid.

18. The process of claim 5 wherein the chelating agent is ethylene-N,N'-2 aminomethyl) -pyridine-N,N'-diacetic acid.

References (lited by the Examiner UNITED STATES PATENTS 2,506,492 5/50 De Mytt et al 167--87 .1 2,631,965 3/53 Schnell 16787.1 2,990,336 6/61 Martin 16787.1 3,017,364 1/62 Henry 16787.1 3,099,603 7/63 Banker et al 16787 .1

OTHER REFERENCES Li et al., JACS, 77 (20); pp. 52255228, October 20, 1955.

Sequestrene Booklet, 54 pages, page 21.

Martell et al., Chemistry of the Metal Chelate Compounds, Prentice-Hall, Inc., New York (1952) page 383.

Chemical Abstracts 53; p. 826b (1959).

Chemical Abstracts 54; p. 638ld (1960).

JULIAN S. LEVITT, Primary Examiner.

FRANK CACCIAPAGLIA, 1a., Examiner. 

1. A COMPOSTION IN PWDER FORM SUITABLE FOR USE, WHEN IN AQUEOUS SOLUTION, IN THE COLD PERMANENT WAVING OF HAIR COMPRISING: (A) AT LEAST ONE MEMBER SELECTED FROM THE GROUP CONSISTING OF A WATER-SOLUBLE THIOGLYCOLIC ACID COMPLEX OF A METAL ION AND WATER-SOLUBLE ALKALI METAL, AMMONNIUM AND LOWERR ALKANOLAMINO SALTS THEREOF WHEREIN THE METAL ION IS SELECTED FROM THE GROUP CONSISTING OF ZINC, CALCIUM, STRONTIU, BARIUM, CADMIUM, ALUMINUM, AND NICKEL, AND (B) A CHELATING AGENT SELECTED FROM THE GROUP CONSISTING OF WATER-SOLUBLE POLYAMINOPOLYCARBOXYLIC ACIDS AND ALKALI METAL, AMMONIUM AND LOWER ALKNAOLAMINO SALTS THEREOF, SAID CHELATING AGENT HAVING A METAL CHELATE FORMATION CONSTANT WITH THE METAL ION OF COMPONENT (A) AT LEAST EQUAL TO THE STABILITY CONSTANT OF THE CORRESPONDING METAL ION COMPLEX OF (A), AND BEING PRESENT IN AT LEAST AN AMOUNT SUCH THAT ON SOLUTION OF THE POWDER A SUBSTANTIAL PROPORTION OF THE METAL ION IS REMOVED FROM THE METAL ION COMPLEX OF (A) THROUGH THE FORMATION OF A MORE STABLE CHELATE WITH SAID CHELATING AGENT, SAID COMPOSTION HAVING A PH WITHIN THE RANGE FROM ABOUT 8.5 TO ABOUT 10 WHEN IN AQUEOUS SOLUTION. 